QMetaMethod 类

QMetaMethod 类提供有关成员函数的元数据。更多...

头：	#include <QMetaMethod>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core

公共类型

enum	Access { Private, Protected, Public }
enum	MethodType { Method, Signal, Slot, Constructor }

公共函数

QMetaMethod::Access	access () const
`(从 6.5 起)` bool	invoke (QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
`(从 6.5 起)` bool	invoke (QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const
`(从 6.5 起)` bool	invoke (QObject * obj , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
`(从 6.5 起)` bool	invoke (QObject * obj , Args &&... arguments ) const
`(从 6.5 起)` bool	invokeOnGadget (void * gadget , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
`(从 6.5 起)` bool	invokeOnGadget (void * gadget , Args &&... arguments ) const
`(从 6.2 起)` bool	isConst () const
bool	isValid () const
int	methodIndex () const
QByteArray	methodSignature () const
QMetaMethod::MethodType	methodType () const
QByteArray	name () const
int	parameterCount () const
`(从 6.0 起)` QMetaType	parameterMetaType (int index ) const
QList<QByteArray>	parameterNames () const
int	parameterType (int index ) const
`(从 6.0 起)` QByteArray	parameterTypeName (int index ) const
QList<QByteArray>	parameterTypes () const
`(从 6.0 起)` int	relativeMethodIndex () const
`(从 6.0 起)` QMetaType	returnMetaType () const
int	returnType () const
int	revision () const
const char *	tag () const
const char *	typeName () const

静态公共成员

QMetaMethod

fromSignal (PointerToMemberFunction signal )

bool	operator!= (const QMetaMethod & m1 , const QMetaMethod & m2 )
bool	operator== (const QMetaMethod & m1 , const QMetaMethod & m2 )

宏

Q_METAMETHOD_INVOKE_MAX_ARGS

详细描述

QMetaMethod 拥有 methodType ()， methodSignature (), 列表化的 parameterTypes () 和 parameterNames (), a return typeName ()， tag (), and an access () specifier. You can use invoke() to invoke the method on an arbitrary QObject .

另请参阅 QMetaObject , QMetaEnum , QMetaProperty ，和 Qt 的特性系统 .

成员类型文档编制

enum QMetaMethod:: Access

This enum describes the access level of a method, following the conventions used in C++.

常量	值
`QMetaMethod::Private`	`0`
`QMetaMethod::Protected`	`1`
`QMetaMethod::Public`	`2`

enum QMetaMethod:: MethodType

常量	值	描述
`QMetaMethod::Method`	`0`	函数是纯成员函数。
`QMetaMethod::Signal`	`1`	函数是信号。
`QMetaMethod::Slot`	`2`	函数是槽。
`QMetaMethod::Constructor`	`3`	函数是构造函数。

成员函数文档编制

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

Invokes this method on the object object 。返回 true 若成员可以被援引。返回 false 若没有这样的成员或参数不匹配。

For the overloads with a QTemplatedMetaMethodReturnArgument parameter, the return value of the member function call is placed in ret . For the overloads without such a member, the return value of the called function (if any) will be discarded. QTemplatedMetaMethodReturnArgument is an internal type you should not use directly. Instead, use the qReturnArg() function.

The overloads with a Qt::ConnectionType type parameter allow explicitly selecting whether the invocation will be synchronous or not:

若 type is Qt::DirectConnection , the member will be invoked immediately in the current thread.
若 type is Qt::QueuedConnection ， QEvent will be sent and the member is invoked as soon as the application enters the event loop in the thread the obj was created in or was moved to.
若 type is Qt::BlockingQueuedConnection , the method will be invoked in the same way as for Qt::QueuedConnection , except that the current thread will block until the event is delivered. Using this connection type to communicate between objects in the same thread will lead to deadlocks.
若 type is Qt::AutoConnection , the member is invoked synchronously if obj lives in the same thread as the caller; otherwise it will invoke the member asynchronously. This is the behavior of the overloads that do not have the type 参数。

To asynchronously invoke the animateClick () slot on a QPushButton :

int methodIndex = pushButton->metaObject()->indexOfMethod("animateClick()");
QMetaMethod method = metaObject->method(methodIndex);
method.invoke(pushButton, Qt::QueuedConnection);

With asynchronous method invocations, the parameters must be copyable types, because Qt needs to copy the arguments to store them in an event behind the scenes. Since Qt 6.5, this function automatically registers the types being used; however, as a side-effect, it is not possible to make calls using types that are only forward-declared. Additionally, it is not possible to make asynchronous calls that use references to non-const-qualified types as parameters either.

要同步援引 compute(QString, int, double) slot on some arbitrary object obj 检索其返回值：

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QString, int, double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj, Qt::DirectConnection, qReturnArg(retVal),
              QString("sqrt"), 42, 9.7);

若 compute 槽不接受恰好一个 QString , one int , and one double in the specified order, the call will fail. Note how it was necessary to be explicit about the type of the QString , as the character literal is not exactly the right type to match. If the method instead took a QByteArray ， qint64 ，和 long double , the call would need to be written as:

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QByteArray, qint64, long double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj, Qt::DirectConnection, qReturnArg(retVal),
              QByteArray("sqrt"), qint64(42), 9.7L);

The same call can be executed using the Q_ARG () 和 Q_RETURN_ARG () macros, as in:

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QString, int, double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj,
              Qt::DirectConnection,
              Q_RETURN_ARG(QString, retVal),
              Q_ARG(QString, "sqrt"),
              Q_ARG(int, 42),
              Q_ARG(double, 9.7));

警告： this method will not test the validity of the arguments: object must be an instance of the class of the QMetaObject of which this QMetaMethod has been constructed with.

该函数在 Qt 6.5 引入。

另请参阅 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

Invokes this method on a Q_GADGET 。返回 true 若成员可以被援引。返回 false 若没有这样的成员或参数不匹配。

指针 gadget must point to an instance of the gadget class.

援引始终是同步的。

For the overload with a QTemplatedMetaMethodReturnArgument parameter, the return value of the member function call is placed in ret . For the overload without it, the return value of the called function (if any) will be discarded. QTemplatedMetaMethodReturnArgument is an internal type you should not use directly. Instead, use the qReturnArg() function.

警告： this method will not test the validity of the arguments: gadget must be an instance of the class of the QMetaObject of which this QMetaMethod has been constructed with.

该函数在 Qt 6.5 引入。

另请参阅 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().

QMetaMethod::Access QMetaMethod:: access () const

Returns the access specification of this method (private, protected, or public).

注意： Signals are always public, but you should regard that as an implementation detail. It is almost always a bad idea to emit a signal from outside its class.

另请参阅 methodType ().

`[static]` template <typename PointerToMemberFunction> QMetaMethod QMetaMethod:: fromSignal ( PointerToMemberFunction signal )

返回的元方法相当于给定 signal ，或无效 QMetaMethod if signal is nullptr or not a signal of the class.

范例：

QMetaMethod destroyedSignal = QMetaMethod::fromSignal(&QObject::destroyed);

`[since 6.2]` bool QMetaMethod:: isConst () const

Returns whether the method is const qualified.

注意： This method might erroneously return false for a const method if it belongs to a library compiled against an older version of Qt.

该函数在 Qt 6.2 引入。

bool QMetaMethod:: isValid () const

返回 true if this method is valid (can be introspected and invoked), otherwise returns false .

int QMetaMethod:: methodIndex () const

返回此方法的索引。

QByteArray QMetaMethod:: methodSignature () const

返回此方法的签名 (如 setValue(double) ).

另请参阅 parameterTypes () 和 parameterNames ().

QMetaMethod::MethodType QMetaMethod:: methodType () const

返回此方法 (信号、槽或方法) 的类型。

另请参阅 access ().

QByteArray QMetaMethod:: name () const

返回此方法的名称。

另请参阅 methodSignature () 和 parameterCount ().

int QMetaMethod:: parameterCount () const

返回此方法的参数数。

另请参阅 parameterType () 和 parameterNames ().

`[since 6.0]` QMetaType QMetaMethod:: parameterMetaType ( int index ) const

Returns the metatype of the parameter at the given index .

若 index is smaller than zero or larger than parameterCount (), an invalid QMetaType 被返回。

该函数在 Qt 6.0 引入。

另请参阅 parameterCount (), returnMetaType ()，和 QMetaType .

QList < QByteArray > QMetaMethod:: parameterNames () const

返回参数名称的列表。

另请参阅 parameterTypes () 和 methodSignature ().

int QMetaMethod:: parameterType ( int index ) const

Returns the type of the parameter at the given index .

The return value is one of the types that are registered with QMetaType ，或 QMetaType::UnknownType if the type is not registered.

另请参阅 parameterCount (), parameterMetaType (), returnType ()，和 QMetaType .

`[since 6.0]` QByteArray QMetaMethod:: parameterTypeName ( int index ) const

Returns the name of the type at position index If there is no parameter at index , returns an empty QByteArray

该函数在 Qt 6.0 引入。

另请参阅 parameterNames ().

QList < QByteArray > QMetaMethod:: parameterTypes () const

Returns a list of parameter types.

另请参阅 parameterNames () 和 methodSignature ().

`[since 6.0]` int QMetaMethod:: relativeMethodIndex () const

Returns this method's local index inside.

该函数在 Qt 6.0 引入。

`[since 6.0]` QMetaType QMetaMethod:: returnMetaType () const

Returns the return type of this method.

该函数在 Qt 6.0 引入。

另请参阅 parameterMetaType (), QMetaType ，和 typeName ().

int QMetaMethod:: returnType () const

Returns the return type of this method.

The return value is one of the types that are registered with QMetaType ，或 QMetaType::UnknownType if the type is not registered.

另请参阅 parameterType (), QMetaType , typeName ()，和 returnMetaType ().

int QMetaMethod:: revision () const

Returns the method revision if one was specified by Q_REVISION , otherwise returns 0.

const char *QMetaMethod:: tag () const

Returns the tag associated with this method.

Tags are special macros recognized by moc that make it possible to add extra information about a method.

Tag information can be added in the following way in the function declaration:

    // In the class MainWindow declaration
    #ifndef Q_MOC_RUN
    // define the tag text as empty, so the compiler doesn't see it
    #  define MY_CUSTOM_TAG
    #endif
    ...
    private slots:
        MY_CUSTOM_TAG void testFunc();

and the information can be accessed by using:

    MainWindow win;
    win.show();
    int functionIndex = win.metaObject()->indexOfSlot("testFunc()");
    QMetaMethod mm = win.metaObject()->method(functionIndex);
    qDebug() << mm.tag(); // prints MY_CUSTOM_TAG

For the moment, moc will extract and record all tags, but it will not handle any of them specially. You can use the tags to annotate your methods differently, and treat them according to the specific needs of your application.

注意： moc expands preprocessor macros, so it is necessary to surround the definition with #ifndef Q_MOC_RUN , as shown in the example above.

const char *QMetaMethod:: typeName () const

返回此方法的返回类型名称。

另请参阅 returnType () 和 QMetaType::type ().

宏文档编制

Q_METAMETHOD_INVOKE_MAX_ARGS

Equals maximum number of arguments available for execution of the method via QMetaMethod::invoke()

QMetaMethod 类

公共类型

公共函数

静态公共成员

相关非成员

宏

详细描述

成员类型文档编制

enum QMetaMethod:: Access

enum QMetaMethod:: MethodType

成员函数文档编制

[since 6.5] template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

[since 6.5] template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

[since 6.5] template <typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

QMetaMethod::Access QMetaMethod:: access () const

[static] template <typename PointerToMemberFunction> QMetaMethod QMetaMethod:: fromSignal ( PointerToMemberFunction signal )

[since 6.2] bool QMetaMethod:: isConst () const

bool QMetaMethod:: isValid () const

int QMetaMethod:: methodIndex () const

QByteArray QMetaMethod:: methodSignature () const

QMetaMethod::MethodType QMetaMethod:: methodType () const

QByteArray QMetaMethod:: name () const

int QMetaMethod:: parameterCount () const

[since 6.0] QMetaType QMetaMethod:: parameterMetaType ( int index ) const

QList < QByteArray > QMetaMethod:: parameterNames () const

int QMetaMethod:: parameterType ( int index ) const

[since 6.0] QByteArray QMetaMethod:: parameterTypeName ( int index ) const

QList < QByteArray > QMetaMethod:: parameterTypes () const

[since 6.0] int QMetaMethod:: relativeMethodIndex () const

[since 6.0] QMetaType QMetaMethod:: returnMetaType () const

int QMetaMethod:: returnType () const

int QMetaMethod:: revision () const

const char *QMetaMethod:: tag () const

const char *QMetaMethod:: typeName () const

相关非成员

[noexcept] bool operator!= (const QMetaMethod & m1 , const QMetaMethod & m2 )

[noexcept] bool operator== (const QMetaMethod & m1 , const QMetaMethod & m2 )

宏文档编制

Q_METAMETHOD_INVOKE_MAX_ARGS

内容

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

`[since 6.5]` template <typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , Args &&... arguments ) const

`[since 6.5]` template <typename ReturnArg, typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

`[static]` template <typename PointerToMemberFunction> QMetaMethod QMetaMethod:: fromSignal ( PointerToMemberFunction signal )

`[since 6.2]` bool QMetaMethod:: isConst () const

`[since 6.0]` QMetaType QMetaMethod:: parameterMetaType ( int index ) const

`[since 6.0]` QByteArray QMetaMethod:: parameterTypeName ( int index ) const

`[since 6.0]` int QMetaMethod:: relativeMethodIndex () const

`[since 6.0]` QMetaType QMetaMethod:: returnMetaType () const

`[noexcept]` bool operator!= (const QMetaMethod & m1 , const QMetaMethod & m2 )

`[noexcept]` bool operator== (const QMetaMethod & m1 , const QMetaMethod & m2 )